Process of producing solvents



Patented July 28, 1942 STAT-i E. S t "i i? FE E PRQCESS OF PRODUCING SQLVENTS N0 Drawing. Application July 13, 1940, Serial No. 345,444

2 Claims. (Cl. 196 51 The present invention relates to a process for the recovery of valuable liquids from hydrocarbons containing oxygenated compounds.

An object of the present invention is a production of solvents of lower boiling range from hydrocarbons of higher boiling range, said hydrocarbons characterized by content of oxygenated compounds.

Another object of the present invention is the production of solvents of lower boiling range from liquid and solid hydrocarbons of higher boiling range, said liquid and solid hydrocarbons being characterized by the presence of oxygenated organic compounds.

Still another object of the present invention is the conversion of liquid and solid hydrocarbons, substantially in entirety, into solvents of lower boiling range; said liquid and solid hydrocarbons being characterized by content of oxygenated compounds.

A more specific object of the invention is the conversion of tars and fractions thereof, substantially in entirety, into lower boiling solvents of superior quality; said tars and fractions thereof being characterized by the presence of oxygenated organic compounds.

The tars and fractions thereof forming suitable starting material for the process of the present invention are of oxygen content and are derived from coal, wood, petroleum or gas and are charvation. Selected fractions of the foregoing tars, $1

as for instance pitch or high boiling residues or fractions thereof, serve as suitable starting material.

Coal tar products, and especially coal tar solvents, are meeting serious competition from petroleum solvents, as for instance solvents of olefinic, and naphthenic character, aromatic extracts of petroleum, and the hydrogenated and/ or dehydrogenated naphthas of petroleum. In fact, it is a matter of record that certain coal tar solvents have had to take serious price reductions because of petroleum solvent competition.

Coal tar is an important source of aromatics, available in large quantities and relatively cheap. Conversion of coal tar or fractions thereof, substantially in their entirety, into solvents is a thing much to be desired.

The process of the present invention provides a convenient method for converting said tars or fractions thereof of oxygen content into solvents of high aromaticity, as more fully explained in the following.

The following examples are illustrative only and in no way serve to circumscribe the solvents of possible manufacture from tar or fractions thereof, of oxygen content, as a starting material.

Coal tar containing oxygenated compounds will be shown as the starting material of the cited example, but it is immediately apparent that other tars or fractions thereof of aromatic content, as mentioned in the foregoing, serve as suitable starting materials.

Coal tar is a destructive distillate of coal, generally having a preponderance of fractions boiling above 190 C., a typical specific gravity of 1.120, characterized by content of oxygenated organic compounds, and in its higher boiling range represents molecular complexes that may be viewed as a multiplicity of ring structures.

In my copending application Serial No. 341,593 filed June 20, 1940, a method is described for the conversion of tars or fractions thereof of aromatic content, substantially in their entirety, into superior solvents, said conversion being characterized by being step-wise.

It was further statedin said application that as far as applicant understood the process thereof the same was predicated in the following:

First: By depolymerizing the molecular complexes in step-wise fashion they are finally brought down to the solvents of the invention, without substantial carbon deposit.

Second: That reaction conditions on said molecular complexes, whose solvency is not directly usable, converts said molecular complexes into solvents whose solvency is directly usable, and

Third: Said molecular complexes must be, to conform to the invention, depolymerized under conditions that induce no substantial quantity of normally liquid products that are other than aromatic. By the term Substantial as used therein was meant that the products of said invention were at least substantially 50% aromatic.

Viewed broadly, said invention provided a process wherein, among other things, coal tar or the like was subjected to the action of hydrogen under controlled conditions whereby the high molecular complexes of said starting material Were reduced, including in size, in step-wise manner substantially in entirety, whereby to produce solvents of lowered and controlled boiling range, said solvents being characterized by having directly usable aromaticity as opposed to the high boiling fractions of said starting material comprising high molecular complexes whose solvency is not directly usable, or partially or totally absent.

The present invention provides a method for enhancing the induction of solvency as described in aforesaid copending application.

It has now been found that when converting tars containing high molecular complexes, said tars being characterized by content of oxygenated organic compounds, to solvents of superior solmaterial that influences decompositionaof oxygenated organic compounds contained in the starting material while under the influence of hydrogen. By the specific provision of the inclusion of a catalytic material or materialsadapted to influence decomposition of said oxygenated organic compounds, .while subjected to hydrogen action, the process which induces solvency and converts aforenamed tars of-oxygen-content ina step-wise manner into aforenamed. solvents, is

enhanced.

Included among those materia'lsadapted to influence the decomposition of oxygenated: organic 1 compounds," while holding the? startingmaterial containing 'saidoxygenated organic compounds.- under the influence of hydrogen, are halids, halo-1' gens, and derivatives thereof.

The following examples will serve toiillu'strate modes of practicing the present invention, said. practice being characterized by theitinclusion of catalytic material or' materials; hereinafter referred-to "as decomposition influencersghadaptedi to influence the decomposition of: oxygenated organic compounds contained in the starting material while said starting'm'aterial is-csubjected to the action of hydrogen.

Example I .-Coal tar,'specific g ravity'1.'l20 and distilling substantially 3% at 210 'C. was charged to a bomb designed to'withstandhigh .temperature and high pressure; catalyst molybdenum sulfide and tin chloride. in to an upper pressure of 1,475. pounds.

run continued for in the order of 1..hour, the

' meanwhile keeping the bomb agitated. At the end of said run the bomb was allowed to cool and: the beneficiated tar withdrawn therefrom and inspected. The solvency was found to be enhanced as'is believed, because'of the presence'of the decompoistion influencer that influenced the decomposition of oxygenated organicicompounds" contained in the starting tar.

The beneflciated tar, which hadibeen processed in'the liquid phase, was distilled toangup'per limit of-substantially 300 0. whereby to recover substantially 28 as the solvent of the" present invention having an .aromaticity of in the order of at least 50%; .The. residue resulting: from dis- .tillation recovery of thesolvent of the present invention, was charged back to the-bomb with addition of fresh starting tar to compensate for 1 .reduction involume incidental to said distillation, L andthe process'repeated in the presence of simi- Thebeneficiated aterial lat catalytic material. was again'distilled to an upper limit of substaninventionhaving an aromaticity of substantially 50% or more.

Hydrogen was pumped Heat: was applied to an upper limit of 400 C., and the:

Recurring cycles ofr. '.preferred, as for instance, a temperature chosen .10 from the range of 300 C. to 500 0.; however, lower temperatures are usable. Pressures chosen from the range above 200 atmospheres are preferred; however, lower pressures are usable. Thus, under the action of hydrogen while conif) tacting a decomposition influencer, the starting tar. .under. temperature. and pressurev conditions .chosentfromin'exces's' of 30053 0.. and 200 atmospheres; respectively, iSlCOllVGItEd :to solvents boiling .(as. anzexample). below 300 :0; said solvent .zugbeing characterized by substantially 50% aroi maticxcontentyor. more, and. beingfurther-char- :acterized ;by;.being products flowing :from: stepwise reduction of a multiplicity of rings :as afore- :pmentioned;;said solvents being still, further char- .iacterized 'as 1' being ;that producti'flowing from ring reduction,.iincluding .in sizewherein said reduction :.is: accomplished under; coordinated time, temperature, and pressure'rconditions that preclude carbonaceous deposition of any sub- 3o...stantial percentage. .Said' carbonaceous deposi- .1; tionreferringto any time or period-of the process .1 wherein processcontrols-areimpressed; for multi- -:plicity of. ring reduction for formation "of the sol- .9 vent of the present invention. Said solvents maybe further "refined-as for instance for reduction, unspecific-gravity, viscosity, etc.; whichstatmentincludes further ac- 1.; tion ::of :-.or' by; hydrogen, -which-forms no part .".Of thepresent invention-inasmuch, as the present 40 invention is only :concerned with that treatment of tar in liquid phase i-in thepresence of :a decompositioni influencer --,which includes depolymerizatiorrof: ring multiplicity in the manner described whereby-to :produce solvents. 5 Viewed-broadly, :the, present'invention provides T. a process for, subjecting tars-ofoxygen and ring multiplicitycontent. derivedfrom -coal,---wood, petroleum; or gas to theactionofhydrogen while under, the influence ofra decomposition influ- 59 encer, one or more-times soas to induce solvency of usable quality, as opposed to; ring multiplicities not characterized bysolvent utility.

The present invention includes,..-otherthan intermittent operation as for instance in a bomb, continuous operation .inmeaction -chamber, a series of.chambers,,.a .parallelismthereof, in-

cludinga multiplicity. thereof, .wherein said tar is flowed with hydrogenunder the influenceof said decomposition influencer,. under...conditions as 60 heretofore stated.

- By the term beneflciated asused herein and in the appended claimsis meant the starting material, orfraction; thereof, at least.once,subjected to the action-ofhydrogen while contacting a decompositioninfluencer for, among other things, depolymerization of-ring .multiples.

By the term depolymerizationis also meant the action of hydrogen on: structures containing a plurality .of rings whereby..to.eff.ectreduction,

. including in size, thus providing the solvents of the-present invention. r

The solvents of the presentinventionare not circumscribed by any certain. boiling.,range but are rather. characterized by...substantial. aromaticity. as heretofore described, and it will be understood that said solvents may serve as substitutes for benzene, toluene, xylene, naphtha and high flash naphtha and various other solvents including plasticizers. Some heavy naphthas or solvents currently available have an end point in the order of 360 C. The present invention provides for cutting the solvent at any desired point with subsequent fractionation into desired cuts as may be dictated by commercial necessity. Any or all residues resulting from the distillation step may be recycled.

The phase condition of the present process is proponderantly liquid and is not that phase which gasifies all the starting materials. The term liquid phase may not be technically correct, but as herein used is meant to differentiate from processes that gasify all material to be processed.

The starting materials of the process are not circumscribed by limitations in carbon content, as any of the tars of aromatic content available may be used. Tars of more than usual carbon content may be depolymerized under less serve conditions at first, with more severe conditions progressively applied until maximum reaction conditions are attained.

Suitable starting materials also include stripped tars and topped tars, as for instance tars that have been stripped of their low boiling ends up to 220 C. or higher. Tars of aromatic nature are of varying initial boiling points, as an example, an aromatic tar of petroleum origin whose initial boiling point is in the order of 250 C.

Many modes of practicing the present invention are possible as will be apparent to those skilled in the art. For instance, tar may be stripped of any desired percentage of low ends and the residual mass then treated in accordance with present teachings to provide the productssolvents-of the present invention.

Thus, pitches, hard or soft, are among the starting materials of the process; also included in starting materials of the present process, are those residual portions of tar, more viscous than said parent material, that result from removal of low boiling ends. Viewed broadly, the starting materials of the present process are tars and fractions thereof.

Those skilled in the art know that hydrogenations proceed at low pressures; however, commercial recoveries are best effected at elevated pressures, thus the present invention includes use of pressures as high as practicable. The time of treatment may be as short as 1 hour, or less; however, tars of appreciable carbon content may require longer periods.

The starting materials of the process include tar cr tar fractions at least once refined hydrogen.

The solvents of the present invention are varied in boiling range and include any or all of the following ranges:

Product Boiling range, C. Benzol 78-120 Toluol 100-150 Hi-flash naphtha 150-200 High boiling crudes 150-350 Plasticizers 160-360 Instead of controlling the process to provide a low end of 78 C., as noted in the benzol shown, processing may be controlled to produce lower boiling products.

The induced solvents of the present process may be further characterized by their containing fractions boiling at least 150 C. to 200 C.

Thus, it will be seen that the process may be carried forward to induce the low boiling points of any of the noted solvents, or. others. Inasmuch as solvent specifications are continually changing, and new arts require solvents of constantly changing characteristics, the solvents of the present invention are not characterized by any definite boiling range but are rather characterized by an aromaticity as heretofore explained, and further characterized by being conversion products, at least to a degree, of the high molecular complexes as aforestated.

Pitch, high residues and fractional parts of tar, crude or refined by hydrogen, are also preferred starting materials of the process.

Example II.A coal tar residual product, boiling 15% at 355 C., and having a specific gravity greater than 1, is subjected to the action of hydrogen in the presence of tin sulfide and iodoform, with a temperature chosen from the range 300-500 C. and a pressure above 50 atmospheres for such a length of time as to induce an initial boiling point below 200 C. The beneficiated material is distilled to an upper limit of 290 C. to recover the solvent of the present invention, said solvent characterized by having an aromaticity of in the order of 50% or more. The residue resulting from said distillation being recycled to the end that substantially total conversion, as heretofore noted, is effected; said conversion products are also characterized by an aromaticity of in the order of 50% or more.

Thus, it will be seen that the present invention broadly includes subjecting tar fractions boiling predominantly above C. to the action of hydrogen with temperature and pressure conditions so coordinated as to produce liquid phase whereby to produce solvents of substantial aromatic percentage, said solvents being characterized by being step-wise conversion products of molecular complexes, said molecular complexes having been subjected to process variables in such manner as to provide substantially total conversion.

The step-wise conversion of the starting material also includes conversion of lower boiling fractions to the solvents of the present invention, which statement is predicated on the substantially total conversion of the starting materials to solvents.

The term coal tar as used herein means a tar produced by high temperature carbonization of coal, as for instance, high temperature coke oven tar or gas house tar.

Catalysts assist in speeding and directing the desired reaction of the process of the present invention. In addition to catalyst previously mentioned, all hydrogenating catalyst are usable therewith, but those having substantial sulphur poisoning immunity are desirable; metals of the sixth or eighth group (periodic) or compounds thereof, such as sulfides and/or oxides. Various catalyst forms may be used, such as various shapes; deposited in Well-known manners on carriers; cobalt, tin, molybdenum, vanadium, chromium, or their compounds. promoted or in admixtures, as for instance with small amounts of acids and/or halogen derivatives; all catalyst of known hydrogenating efiicacy in the form of shapes, pellets, extruded lengths, comminuted; with or without the presence of other materials possessing hydrogenating properties, or not, such as asbestos, lumps of brick, quartz, etc.

Recovery of the solvents by means other than distillation is herein considered as the equivalent of distillation recovery.

Intermittent and/or batch operation, which statement broadly covers combination thereof, may be incorporated in the foregoing examples, or obvious mechanical or chemical equivalents may bezsubstituted within the spirit of the present invention;

I claim:

1. In the production of solvents from a mixture of 'high temperature coal tar fractions the process which comprises: subjecting said mixture of tar fractions to the action of hydrogen while contacting as catalytic material a sulfide of a metal and iodoform at a pressure in excess of atmospheric and a temperature selected between the limits of ZOO-600 C. and for such a length of time as to provide newly formed low boiling fractions boiling at least as low as about 78 C.; stripping the beneficiated material to provide relatively low boiling solvent material boiling at least as low as aboutw78 C. and being: further characterized by'an upper boilingpoint at least as high as about 200 C.

2. In the production of solvents from a mixture of high temperature coal tar fractions the process which comprises: subjecting said mixture of tar fractions toithe action of hydrogen while contacting as catalytic material tin sulfide and iodoform at a pressure. in excess of atmospheric and a temperature. selected between the limits of 200-600 C. and for such a length of time as to provide newly formed low boiling fractions boiling at least as low as'about 78 C.; stripping the beneficiated material to provide relatively low boiling solvent material boiling at least as low as about 78 C. and being further characterized by an upper boiling point at least as high as about 200 C.

JACQUELIN E. HARVEY, JR. 

